Bonding and Structures of Silicon Oxides and Chlorides

Steps:

• SiO₂ bonding is covalent due to moderate electronegativity difference (Si 1.8, O 3.5), forming strong Si-O bonds.
• SiO₂ structure is giant covalent lattice, with each Si tetrahedrally bonded to 4 O atoms in a 3D network.
• SiCl₄ bonding is covalent, as Si shares electrons with 4 Cl atoms in discrete tetrahedral molecules.
• SiCl₄ structure is simple molecular, with molecules held by weak intermolecular forces.

Why B is correct:

• B accurately classifies SiO₂ as covalent giant (network solid) and SiCl₄ as covalent simple (molecular compound), aligning with Fajans' rules for polarization in silicon compounds.

Why the others are wrong:

• A: Erroneously gives SiCl₄ a giant structure; it is discrete molecules, not a lattice.
• C: Incorrectly assigns ionic bonding to SiO₂; electronegativity favors covalent character.
• D: Falsely labels SiO₂ bonding as ionic, ignoring its covalent network.

Final answer: B